Conventionally, such kind of an air conditioner for a vehicle is disclosed in, for example, Patent Literature 1. According to an air conditioner for a vehicle of Patent Literature 1, a warm-air passage passing a heater core (i.e., a heating heat exchanger) is formed in an air conditioning case. Further, cold-air bypass paths bypassing the heater core is formed on both sides of the warm-air passage in an upper-lower direction.
A first air-mix door opens or closes an upper portion of the warm-air passage and an upper cold-air passage, and a second air-mix door opens or closes a lower portion of the warm-air passage and a lower cold-air passage. The two air-mix doors are configured by a cantilever door. The two air-mix doors are operated by an electric motor through a link mechanism to interlock with each other. The link mechanism is arranged outside of the air conditioning case and is located between the heater core and an evaporator (i.e., a cooling heat exchanger) when viewed in an axial direction of a shaft of the air mix door.
On the other hand, Patent Literatures 2 to 5 disclose an air conditioner for a vehicle, a first air-mix door and a second air-mix door of which is configured by a slide door that has a plate shape and moves slidably.